WHAT IS THE ANSWER

Open the tax return and then click "File" on your computer menu bar, select "Encrypt" and you will be prompt with password dialog.

This does not work. Following instructions, created password for a file. Upon reopening TurboTax Home & Business and opening file, it does not prompt for password.

@kduffy1a - There is a check box on the password screen that says "Remember this password (add to keychain)".

If checked then the Mac keychain will automatically supply the password so you do not need to type it.  That is a Mac feature and has nothing to do with TurboTax.   Use the Mac "help" menu to learn about keychain and how to remove unwanted entries.

Open the tax return and then click "File" on your computer menu bar, select "Encrypt" and you will be prompt with password dialog.